$ { \left[\begin{array}{rr}{2} & {-1} \\ {-1} & {0} \\ {0} & {3}\end{array}\right]+\left[\begin{array}{rr}{2} & {0} \\ {1} & {1} \\ {4} & {-2}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}+{2} & {-1}+{0} \\ {-1}+{1} & {0}+{1} \\ {0}+{4} & {3}+{-2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{4} & {-1} \\ {0} & {1} \\ {4} & {1}\end{array}\right]}$